1. Field of the Invention
The present invention relates to an interconnect mechanism for dual lock, and more particularly to an interconnect mechanism for dual lock with simultaneous retraction of a latch bolt and deadbolt by an inside lever handle.
2. Description of the Related Art
It is known to provide door locks with a latch bolt lock, a deadbolt lock, and a mechanism interconnecting the latch bolt and the deadbolt so that in an emergency both bolts may be simultaneously retracted upon operation of a single actuating means provided on the inside of a door, thereby permitting rapid egress from a secured area. For example, U.S. Pat. No. 3,910,613 to Nolin issued on Oct. 7, 1975 discloses a panic proof lock set; U.S. Pat. No. 3,999,789 to Maurits et al. issued on Dec. 28, 1976 discloses a lock of the type enabling panic exit; and U.S. Pat. No. 4,129,019 to Urdal issued on Dec. 12, 1978 discloses a cartridge device for joining two independent lock devices.
U.S. Pat. No. 5,657,653 to Hensley et al. issued on Aug. 19, 1997 discloses a dual lock with simultaneous retraction of latch and deadbolt by an inside lever handle and uncoupler between the driving spindle and the lever handle to solve complex configurations in known mechanism for interconnecting the latch bolt to the deadbolt for simultaneous operation. It is, however, found that screws 178 might cause an obstacle to rotation of the upper cam 166 if the heads of screws 178 are not completely received in the countersunk holes 176. Similarly, screws 184 might cause an obstacle to rotation of the lower cam 160 if the heads of screws 184 are not completely received in the countersunk holes 182. In addition, the vertically extending ribs 175 on the trim plate 162 may have a difference in the heights thereof after manufacturing and thus cannot provide smooth sliding motion of the slide plate 164. Furthermore, the ribs 175 cannot provide sufficient structural strength to keep planar surface of the trim plate 162 for supporting smooth sliding motion of the slide plate 164. More specifically, the trim plate 162 might be bent during stacking and/or assembly. Further, two L-shaped brackets 172 are provided on each side of the trim plate 162 for guiding sliding motion of the slide plate 164. Formation of the brackets 172 is costly and troublesome and requires precision to avoid too-tight or too-loose engagement with the slide plate 164. Further, the interconnect mechanism 24 and the inside chassis assembly 18 are separate from each other before assembly such that, if the slide plate 164 has not yet engaged with the trim plate 162, the brackets 172 may deform if they are pressed during transportation or package. As a result, sliding motion of the slide plate 164 is not allowed.
The present invention is intended to provide an improved interconnect mechanism for a dual lock that mitigates and/or obviates the above problems.